1. Field of the Invention
The present invention relates to a thermotherapeutic apparatus for curing affected parts inside a patient's body.
2. Description of the Related Art
Thermotherapy is a method of curing cancer which has recently come to public notice. In this treatment, a curer warms the affected part to about 43.degree. C. to kill cancerous cells, knowing that the cancerous cells can be more easily destroyed by heat than normal cells. Disclosed in Japanese Patent Disclosure (KOKAI) No. 60-119962, for example, is a thermotherapeutic apparatus which comprises one external electrode and one internal electrode. This typical thermotherapeutic apparatus is designed so that the internal electrode is inserted into that region of a patient's body cavity which faces a tumor, while the external electrode is set on the outside of the patient's body so as to face the internal electrode across the tumor. A high-frequency oscillator is used to apply a high-frequency voltage between these two electrodes, thereby subjecting the affected part to high-frequency energy. By doing this, the tumorous region can be inductively warmed. Since the internal electrode is adapted to be inserted into the body cavity, its surface is narrower than that of the external electrode, so that the density of the high-frequency energy applied increases as the internal electrode is approached.
Accordingly, the thermotherapeutic apparatus is an effective means of local warming. It is generally known, however, that thermotherapy can enjoy improved efficacy if it is combined with radiotherapy or chemotherapy. Conventionally, therefore, thermotherapy is effected in combination with radiotherapy or chemotherapy. In a typical method of radiotherapy, radiation is applied from outside a patient's body. In this case, however, if the affected part is situated deep in the body, the patient will probably be subjected to general exposure due to excessive irradiation, thus suffering damage to his body.
A new method has recently been proposed to prevent increase of the total amount of irradiation and to apply radiation directly to the affected part of a patient's body. According to this method, a very small radiation source (radiation seed) is made to indwell in the vicinity of the affected part for a limited period of time, by needling or the like. If the affected part is situated close to the body cavity, in particular, the radiation source is introduced into the cavity by using a catheter or the like.
Disclosed in Japanese Patent Disclosure (KOKAI) No. 58-78654 is a catheter which is adapted for localizing diathermic therapy using a radioisotope. With use of this catheter, diathermic therapy and radiotherapy can be exercised simultaneously.
When combining thermotherapy and radiotherapy, however, a plurality of catheters and internal electrodes are retained in the body cavity for a long period of time, so that a patient must stand a great pain. In the treatment method stated in Japanese Patent Disclosure No. 58-78654, moreover, normal tissues will be also exposed to excessive radiation if a radiation source is made to indwell in the body cavity for prolonged thermotherapy.